One Way to Grow Despite Drought? It’s in the Roots

As parts of the world become more arid, researchers have been looking for drought-resistant plants, ways to get the most out of what little water there is. But researchers at the University of Bonn say not enough attention is paid to the roots, which may end up being the root of the solution, rather than the problem.

A new study, led by Frank Hochholdinger of the University of Bonn and Silvio Salvi of the University of Bologna, found a rare mutation in barley, and investigated whether that mutation could be isolated and reproduced. Barley is a fairly important cereal crop in many countries. Germany, where the University of Bonn is located, happens to be the second-leading producer of barley in the world. It’s also a close relative of wheat, and barley genes have already been transplanted to wheat a few times.

This particular mutation affects the roots in a strange way: It causes them to grow straight downwards, deep into the soil, rather than to spread out horizontally closer to the surface. The horizontal spread of most barley is an evolution that makes sense; it allows for the roots to spread over a larger volume of soil, all the better to suck up nutrients, and it also provides some physical stability for the plant.

But growing vertically downwards could allow the roots to tap into water that’s trapped more deeply beneath the surface. And that could, theoretically, allow this mutant variety of barley to survive in a much more arid environment than most barley plants. The researchers named the mutated gene in question “egt2,” which stands for “enhanced gravitropism 2,” a very cool and sci-fi name that basically means, “this plant is obsessed with growing in the direction of gravity.”

It’s worth noting, as the researchers do, that vertically-growing roots would lose the benefits of horizontal roots and so wouldn’t be ideal for many environments. These plants would struggle in, say, the Midwest, which has very rich soils and plenty of rain. But in more arid areas, whether that’s California’s Central Valley, parts of Somalia, Australia and many others, this could be a way to make the most of the very small amounts of water available in the soil.